Effects of teclistamab and talquetamab on soluble BCMA levels in patients with relapsed/refractory multiple myeloma

T cell margination: investigating the detour of T cells following forimtamig treatment in humanized mice

T cell bispecific antibodies (TCBs) are a promising new class of therapeutics for relapsed/refractory multiple myeloma. A frequently observed, yet incompletely understood effect of this treatment is the transient reduction of circulating T cell counts, also known as T cell margination (TCM). After administration of the GPRC5D-targeting TCB forimtamig (RG6234), TCM occurred in patients and correlated with cytokine release and soluble B cell maturation antigen decrease. We demonstrate that TCM is accurately represented in the humanized NSG mouse model and occurs at a lower threshold of target expression than systemic cytokine release. Application of whole-mouse tissue clearing and 3D imaging revealed that T cells accumulate in the bone marrow after treatment. We hypothesize that low amounts of targets are sufficient to rapidly redirect T cells upon TCB engagement. Therefore, we propose TCM as a beneficial, highly sensitive and early effect of forimtamig that leads T cells to likely sites of bone marrow tumor lesions.

BCMA-targeted therapies in multiple myeloma: advances, challenges and future prospects

Multiple myeloma (MM) is hematological cancer characterized by the aberrant proliferation of plasma cells. The treatment of MM has historically presented challenges, with a limited number of patients achieving sustained remission. Recent advancements in the therapeutic landscape have been marked by the development of B-cell maturation antigen (BCMA)-targeted therapies. BCMA, a plasma cell surface protein, is instrumental in the proliferation and survival of myeloma cells. This review aims to critically assess recent developments in BCMA-targeted therapies. The focus is on evaluating their efficacy and accessibility, as well as discussing potential future directions in this field. Emphasis is placed on chimeric antigen receptor (CAR) T-cell therapy and bispecific antibodies as emerging therapeutic strategies. An extensive review of current clinical trials and studies was conducted, centering on BCMA-targeted therapies. This encompassed an analysis of CAR T-cell therapies, which involve the genetic modification of patient T-cells to target BCMA, and bispecific antibodies that bind to both BCMA on myeloma cells and CD3 on T-cells. Clinical trials have demonstrated the efficacy of BCMA-targeted therapies in MM, with some patients achieving complete remission. However, these therapies are associated with adverse effects such as cytokine release syndrome and neurotoxicity. Research efforts are ongoing to reduce these side effects and enhance overall therapeutic effectiveness. BCMA-targeted therapies signify a notable advancement in MM treatment, offering prospects for prolonged remission and potentially curative outcomes. Despite existing challenges, these therapies represent a significant shift in MM management. The review highlights the necessity of ongoing research to optimize these therapies, improve patient outcomes, and increase treatment accessibility.

Teclistamab Dosing in Responders: Modeling and Simulation Results from the MajesTEC-1 Study in Relapsed/Refractory Multiple Myeloma

BACKGROUND

Based on the phase I/II MajesTEC-1 study, the B-cell maturation antigen (BCMA) and cluster of differentiation (CD)3 bispecific antibody, teclistamab, is approved for relapsed/refractory multiple myeloma (RRMM) at a dose of 1.5 mg/kg weekly (QW), with the option to switch to 1.5 mg/kg every other week (Q2W) in patients maintaining complete response (CR) or better for ≥ 6 months on the QW schedule.

OBJECTIVE

We report the pharmacokinetics (PK), pharmacodynamics, and anticancer activity of teclistamab 1.5 mg/kg Q2W, and the PK of teclistamab 3 mg/kg every 4 weeks (Q4W), on the basis of modeling and simulation results from MajesTEC-1.

METHODS

Teclistamab PK was assessed using a population PK approach. Exposure-response analysis was based on individual estimated teclistamab serum trough concentration (Ctrough). The impact of responders switching to Q2W teclistamab dosing on the formation of the key pharmacological species that drive the mechanism of action of teclistamab (i.e., the trimer formed by simultaneous engagement of teclistamab with BCMA on target multiple myeloma cells and CD3 on effector T cells) was estimated using a quantitative systems pharmacology (QSP) model. Additionally, steady-state teclistamab PK and trimer was simulated for the 1.5 mg/kg Q2W and Q4W (3 mg/kg or 1.5 mg/kg) doses.

RESULTS

Median estimated teclistamab serum Ctrough was lower after the first and fourth Q2W doses (14.4 and 11.7 µg/mL, respectively) than after QW doses (20.4 µg/mL) but remained above the 90% maximal effective concentration. No statistically significant exposure-response trend was observed for duration of response (DOR), progression-free survival, or overall survival in responders who switched to teclistamab 1.5 mg/kg Q2W dosing. Despite the lower teclistamab serum Ctrough, the QSP model estimated comparable target cell-biologics-effector cell (TBE) trimer formation, tumor volume reduction, and DOR for responders switching to 1.5 mg/kg Q2W dosing versus not switching. Steady-state exposure metrics and trimer formation with teclistamab 3 mg/kg Q4W were estimated to be comparable with those at 1.5 mg/kg Q2W.

CONCLUSIONS

MajesTEC-1 modeling and simulation results, which contributed to the teclistamab label update, support the approved switch to teclistamab 1.5 mg/kg Q2W in patients maintaining ≥ CR for ≥ 6 months on the QW dose, without negatively impacting clinical efficacy. In addition, it is estimated that the 3 mg/kg Q4W schedule will provide maintenance of response comparable with the 1.5 mg/kg Q2W schedule. Teclistamab 3 mg/kg Q4W dosing will be evaluated in > 800 patients in three phase III studies in early line RRMM (MajesTEC-3, MajesTEC-9, and MonumenTAL-6) and in 100 patients in RRMM in the phase I MajesTEC-10 study.

CLINICAL TRIAL REGISTRATION

NCT03145181 (phase I, 9 May 2017); NCT04557098 (phase II, 21 September 2020).

Comprehensive Review of Bispecific Antibody Constructs In Multiple Myeloma: Affinities, Dosing Strategies and Future Perspectives

Despite significant advancements, multiple myeloma (MM) remains incurable, and there is still a pressing need for new therapeutic strategies with highly selective mechanisms of action and balanced off-target toxicity. In recent years, the development of "off-the-shelf" bispecific antibodies (bsAbs) has significantly enhanced our ability to treat relapsed or refractory MM. Teclistamab, elranatamab (both BCMA × CD3), and talquetamab (GPRC5D × CD3) are approved for treating MM patients who have received at least 3 prior lines of therapy, including a proteasome inhibitor, an immunomodulatory drug, and an anti-CD38 monoclonal antibody. Meanwhile, the range of available bsAbs is rapidly expanding, offering patients and healthcare providers a broad selection of options that vary in target antigens, binding domains, construct designs, dosing regimens, and side effects. As linvoseltamab, alnuctamab, and ABBV-383 (all BCMA × CD3), as well as forimtamig (GPRC5D × CD3) and cevostamab (FcRH5 × CD3) progress through late-stage clinical development, emerging trispecific antibodies are now available that target either 2 different MM-associated antigens or provide additional co-stimulatory signals to prevent T-cell exhaustion. Despite this plethora of therapeutic options, resistance to bsAbs is an inevitability, and the optimal positioning of these drugs within the current MM treatment landscape remains to be determined. In this review, we examine the available data on all clinically accessible bsAbs, evaluating their potential, current limitations, and implications for efficacy and safety, with the aim of achieving deeper responses and longer overall survival for MM patients.

Predictive Role of Soluble B-Cell Maturation Antigen in Short-Term Monitoring of Differently Treated Multiple Myeloma Patients: A Prospective Study

BACKGROUND

The management of multiple myeloma is challenging because the disease is incurable and unexpected relapses can threaten a patient's survival. Several assessment systems are currently available, but they often require invasive or costly procedures (e.g., instrumental bone marrow and whole-body examinations) or rely on non-specific markers in blood and urine that may not be sufficient to assess and monitor the disease.

AIMS

To address some of these limitations, the aim of this study was to evaluate the potential use of soluble B-Cell Maturation Antigen (BCMA), a promising new serum biomarker, as a toll for moniting multiple myeloma patients.

MATERIALS & METHODS

An unselected cohort of 57 newly diagnosed or relapsed myeloma patients was followed up for 6 months after starting a new therapy. Soluble BCMA levels were measured in peripheral blood using a simple and inexpensive ELISA assay.

RESULTS

Soluble BCMA was detectable in peripheral blood by a simple and inexpensive assay in all patients, even in non-secretory disease or during BCMA-targeted therapies, and significant changes in its levels were observed over time. The analysis showed that the decrease in sBCMA at 1 and 6 months reflects the quality of the clinical response to anti-myeloma regimens.

DISCUSSION & CONCLUSION

The data provide interesting insights into the usefulness of sBCMA as a non-invasive tool for early assessment of treatment efficacy. Its simple and cost-effective detection in peripheral blood could provide clinicians with an addiotional resource for monitoring disease progression and tailoring treatment strategies.

Applications of pharmacometrics in drug development

The last two decades have witnessed profound changes in how advanced computational tools can help leverage tons of data to improve our knowledge, and ultimately reduce cost and increase productivity in drug development. Pharmacometrics has demonstrated its impact through model-informed drug development (MIDD) approaches. It is now an indispensable component throughout the whole continuum of drug discovery, development, regulatory review, and approval. Today, applications of pharmacometrics are common in designing better trials and accelerating evidence-based decisions. Newly emerging technologies, especially those from data and computer sciences, are being integrated with existing computational tools used in the pharmaceutical industry at a remarkably fast pace. The new challenges faced by the pharmacometrics community are not what or how to contribute, but which optimal MIDD strategy should be adopted to maximize its value in the decision-making process. While we are embracing new innovative approaches and tools, this article discusses how a variety of existing modeling tools, with differentiated advantages and focus, can work in concert to inform drug development.

Advancements in bispecific antibodies for multiple myeloma: What's new and what lies ahead

Recent advancements in multiple myeloma (MM) treatment-including immunomodulatory drugs, proteasome inhibitors, monoclonal antibodies, and T cell-redirecting therapies like chimeric antigen receptor (CAR) T cells and bispecific antibodies (BsAbs)-have significantly improved patient outcomes. However, MM remains incurable, highlighting the need for novel therapeutic strategies. BsAbs, which simultaneously target a tumor-specific antigen and CD3 on T cells, have shown promising efficacy. Three BsAbs - teclistamab, elranatamab, and talquetamab - have been approved for relapsed or refractory MM, demonstrating response rates of 60 %-74 % and median progression-free survival of approximately 1 year. This review provides a comprehensive overview of the latest advancements in BsAb therapy for MM, focusing on new therapeutic targets such as BCMA, GPRC5D, and FcRH5, recent clinical trial data, safety considerations, and future directions. We discuss tumor-intrinsic mechanisms of resistance, including antigen expression variability and antigen escape, as well as immune-related factors like T-cell exhaustion and an immunosuppressive microenvironment. Future strategies involve integrating BsAbs earlier in treatment, combining them with other agents to enhance efficacy and overcome resistance, and optimizing administration protocols to mitigate adverse effects. By examining these developments, we highlight how BsAbs are reshaping the treatment landscape of MM and underscore the importance of ongoing research to improve survival and quality of life for patients.

Soluble B-cell maturation antigen levels for disease monitoring in oligosecretory and nonsecretory relapsed multiple myeloma

ABSTRACT

Soluble B-cell maturation antigen (sBCMA) is elevated on multiple myeloma (MM) cells. We investigated whether sBCMA levels correlated with other myeloma tumor volume indicators and its utility in monitoring oligosecretory/nonsecretory (O-S/Non-S) MM. In 115 patients with newly diagnosed MM, sBCMA was compared with M-protein levels, bone marrow plasma cells (BMPCs), circulating tumor cells (CTCs), and total diffusion volume (tDV; estimated by whole-body diffusion-weighted magnetic resonance imaging) at diagnosis. sBCMA levels increased significantly with International Staging System stage, chromosome 1q21 gain/amplification, and CTC levels. sBCMA also correlated strongly with %BMPC (r = 0.65) and moderately with tDV (r = 0.55) and paraprotein levels (involved immunoglobulin in IgG and IgA subtypes, r = 0.44 and 0.4; involved free light-chain levels in light-chain-only MM, r = 0.61, all P < .05). Longitudinal changes in sBCMA were consistent with disease status in both 17 O-S/Non-S and other secretory MM cases. Furthermore, sBCMA levels increased as early as 6 months prerelapse in almost all O-S/Non-S relapsed patients. Thus, sBCMA correlates strongly with total tumor volume in MM, as assessed using different modalities. We suggest that sBCMA is useful, not only for monitoring responses in patients with O-S/Non-S MM but also for early relapse detection and prediction.

Monoclonal Antibodies in Relapsed-Refractory Multiple Myeloma

Multiple myeloma is a malignant hematological tumor characterized by the proliferation of clonal plasma cells in the bone marrow causing organ damage. Despite improved survival rates due to the increasing availability of therapeutic options in recent decades, it remains an incurable disease, with most patients ultimately relapsing. Consequently, relapsed/refractory multiple myeloma disease (RRMM) has become a treatment priority. Immunotherapy is the backbone of treatment in RRMM, starting with monoclonal antibodies such as elotuzumab, daratumumab, and isatuximab. The aim of this review is summarizing the results of RRMM trials with monoclonal antibodies and of the principal ongoing trials containing them. Additionally, we put a brief focus on novel drugs (such as bispecific antibodies) to provide a better overview. The advent of monoclonal antibodies has been nothing short of a game-changer for multi-refractory patients. It has opened up a whole new world of possibilities, offering myeloma patients a brighter and more hopeful future, even in the face of relapse.

Forimtamig, a novel GPRC5D-targeting T-cell bispecific antibody with a 2+1 format, for the treatment of multiple myeloma

ABSTRACT

Despite several approved therapies, multiple myeloma (MM) remains an incurable disease with high unmet medical need. "Off-the-shelf" T-cell bispecific antibodies (TCBs) targeting B-cell maturation antigen (BCMA) and G protein-coupled receptor class C group 5 member D (GPRC5D) have demonstrated high objective response rates in heavily pretreated patients with MM; however, primary resistance, short duration of response, and relapse driven by antigen shift frequently occur. Although GPRC5D represents the most selective target in MM, recent findings indicate antigen loss occurs more frequently than with BCMA. Thus, anti-GPRC5D immunotherapies must hit hard during a short period of time. Here, we characterize forimtamig, a novel GPRC5D-targeting TCB with 2+1 format. Bivalent binding of forimtamig to GPRC5D confers higher affinity than classical 1+1 TCB formats correlating with formation of more stable immunological synapses and higher potency in tumor cell killing and T-cell activation. Using an orthotopic mouse model of MM, forimtamig recruited T effector cells to the bone marrow and induced rapid tumor killing even after the introduction of step-up dosing to mitigate cytokine release. Combination of forimtamig with standard-of-care agents including anti-CD38 antibodies, immunomodulatory drugs, and proteasome inhibitors improved depth and duration of response. The combination of forimtamig with novel therapeutic agents including BCMA TCB and cereblon E3 ligase modulatory drugs was potent and prevented occurrence of GPRC5D -negative tumor relapse. Forimtamig is currently being evaluated in phase 1 clinical trials in patients with relapsed and refractory MM for monotherapy and in combination treatments. This trial was registered at www.ClinicalTrials.gov as #NCT04557150.

Bispecific Antibodies as Bridging to BCMA CAR-T Cell Therapy for Relapsed/Refractory Multiple Myeloma

Establishing a strategy for sequencing of T cell-redirecting therapies for relapsed/refractory multiple myeloma (RRMM) is a pressing clinical need. We longitudinally tracked the clinical and immunologic impact of bispecific T cell-engaging antibodies (BsAb) as bridging therapy (BT) to subsequent B-cell maturation antigen-directed chimeric antigen receptor T (CAR-T) cell therapies in 52 patients with RRMM. BsAbs were a potent and safe option for BT, achieving the highest overall response rate (100%) to BT compared with chemotherapy, anti-CD38, or anti-SLAMF7 antibody-based regimens (46%). We observed early CD4+CAR+ and delayed CD8+CAR+ T-cell expansion in patients receiving BsAbs as BT. In vitro cytotoxicity of CAR-T cells was comparable among BT options. Single-cell analyses revealed increased clonality in the CD4+ and CD8+ T-cell compartments in patients with previous exposure to BsAbs at leukapheresis and on day 30 after CAR-T cell infusion. This study demonstrates the feasibility and efficacy of BT with BsAbs for CAR-T cell therapy in RRMM. Significance: CAR-T cell therapy and BsAbs have revolutionized treatment of triple-class refractory multiple myeloma; however, optimal sequencing is unknown. We demonstrate that BT with BsAb before B-cell maturation antigen-directed CAR-T cell therapy is safe and effective, which might have implications for other hematologic malignancies as well. See related commentary by Bal and Costa, p. 10.

Industry Perspective on First-in-Human and Clinical Pharmacology Strategies to Support Clinical Development of T-Cell Engaging Bispecific Antibodies for Cancer Therapy

T-cell-engaging bispecific antibodies (TCEs) that target tumor antigens and T cells have shown great promise in treating cancer, particularly in hematological indications. The clinical development of TCEs often involves a lengthy first-in-human (FIH) trial with many dose-escalation cohorts leading up to an early proof of concept (POC), enabling either a no-go decision or dose selection for further clinical development. Multiple factors related to the target, product, disease, and patient population influence the efficacy and safety of TCEs. The intricate mechanism of action limits the translatability of preclinical models to the clinic, thereby posing challenges to streamline clinical development. In addition, unlike traditional chemotherapy, the top dose and recommended phase II doses (RP2Ds) for TCEs in the clinic are often not guided by the maximum tolerated dose (MTD), but rather based on the integrated dose-response assessment of the benefit/risk profile. These uncertainties pose complex challenges for translational and clinical pharmacologists (PK/PD scientists), as well as clinicians, to design an efficient clinical study that guides development. To that end, experts in the field, under the umbrella of the American Association of Pharmaceutical Scientists, have reviewed learnings from published literature and currently marketed products to share perspectives on the FIH and clinical pharmacology strategies to support early clinical development of TCEs.

Impact of soluble BCMA and non-T-cell factors on refractoriness to BCMA-targeting T-cell engagers in multiple myeloma

ABSTRACT

Adoptive T-cell therapy is a promising therapy for multiple myeloma (MM), but its efficacy hinges on understanding the relevant biologic and predictive markers of response. B-cell maturation antigen (BCMA) is a key target antigen in MM with active development of multiple anti-BCMA T-cell engagers (TCEs) and chimeric antigen receptor T-cell therapies. The regulation of surface BCMA expression by MM cells, which leads to shedding of soluble BCMA (sBCMA), has triggered debate about the significance of sBCMA as a predictive marker and its potential impact on treatment outcomes. To address this, we leveraged whole-genome sequencing and in vitro assays to demonstrate that sBCMA may independently predict primary refractoriness to anti-BCMA therapies. In addition to sBCMA, tumor burden and surface BCMA antigen density collectively influenced the anti-BCMA TCE cytotoxic efficacy. Correlative analyses of 163 patients treated with the anti-BCMA TCE teclistamab validated and further underscored the association between elevated baseline sBCMA (>400 ng/mL) and refractoriness. Importantly, increasing the TCE dose, using TCE against alternative targets (eg, GPRC5D), and gamma secretase inhibitors were able to overcome the high sBCMA levels. These findings highlight the importance of taking into account the baseline sBCMA levels, disease burden, and TCE dose intensity when administering anti-BCMA TCEs, thereby offering critical insights for optimizing therapeutic strategies to overcome specific high-risk features and primary anti-BCMA TCE refractoriness.

Efficacy and safety of teclistamab in patients with relapsed/refractory multiple myeloma after BCMA-targeting therapies

ABSTRACT

Teclistamab is a B-cell maturation antigen (BCMA)-directed bispecific antibody approved for the treatment of patients with triple-class exposed relapsed/refractory multiple myeloma (R/RMM). In the phase 1/2 MajesTEC-1 study, a cohort of patients who had prior BCMA-targeted therapy (antibody-drug conjugate [ADC] or chimeric antigen receptor T-cell [CAR-T] therapy) was enrolled to explore teclistamab in patients previously exposed to anti-BCMA treatment. At a median follow-up of 28.0 months (range, 0.7-31.1), 40 patients with prior BCMA-targeted therapy had received subcutaneous 1.5 mg/kg weekly teclistamab. The median prior lines of treatment was 6 (range, 3-14). Prior anti-BCMA therapy included ADC (n = 29), CAR-T (n = 15), or both (n = 4). The overall response rate was 52.5%; 47.5% of patients achieved very good partial response or better, and 30.0% achieved complete response or better. The median duration of response was 14.8 months, the median progression-free survival was 4.5 months, and the median overall survival was 15.5 months. The most common treatment-emergent adverse events (TEAEs) were neutropenia, infections, cytokine release syndrome, and anemia; cytopenias and infections were the most common grade ≥3 TEAEs. Infections occurred in 28 patients (70.0%; maximum grade 3/4, n = 13 [32.5%]; grade 5, n = 4 [10%]). Before starting teclistamab, baseline BCMA expression and immune characteristics were unaffected by prior anti-BCMA treatment. The MajesTEC-1 trial cohort C results demonstrate favorable efficacy and safety of teclistamab in patients with heavily pretreated R/RMM and prior anti-BCMA treatment. This trial was registered at www.ClinicalTrials.gov as #NCT03145181 and #NCT04557098.

Mechanisms of resistance against T-cell engaging bispecific antibodies in multiple myeloma: implications for novel treatment strategies

Off-the-shelf T-cell-redirecting bispecific antibodies targeting BCMA, GPRC5D, and FcRH5 have high activity in multiple myeloma with a manageable toxicity profile. However, not all patients respond to bispecific antibodies and patients can develop bispecific antibody resistance after an initial response. Mechanisms that contribute to bispecific antibody resistance are multifactorial and include tumour-related factors, such as high tumour burden, expression of T-cell inhibitory ligands, and antigen loss. Resistance due to antigen escape can be prevented by simultaneously targeting two tumour-associated antigens with a trispecific antibody or a combination of two bispecific antibodies. There is also increasing evidence that primary resistance to bispecific antibodies is associated with impaired baseline T-cell function. Long-term exposure to bispecific antibodies with chronic T-cell stimulation further aggravates T-cell dysfunction, which could contribute to failure of disease control. Therapeutic interference with T-cell exhaustion by targeting inhibitory or costimulatory pathways could improve bispecific antibody-mediated antitumour activity. The immunosuppressive microenvironment also contributes to bispecific antibody resistance. CD38-targeting antibodies hold promise as combination partners for bispecific antibodies because of their potential to eliminate CD38+ immune suppressor cells. In conclusion, a better understanding of the mechanisms underlying the absence of disease response has provided novel insights to optimise T-cell activity and bispecific antibody efficacy in multiple myeloma.

T-cell redirecting bispecific antibody treatment in multiple myeloma: current knowledge and future strategies for sustained T-cell engagement

INTRODUCTION

T-cell redirecting bispecific antibodies (BsAbs), targeting B-cell maturation antigen (BCMA) or G-protein - coupled receptor class C group 5 member D (GPRC5D), are efficacious new agents for the treatment of patients with relapsed or refractory MM.

AREAS COVERED

This review discusses the pharmacokinetic properties, efficacy, and safety profile of T-cell redirecting BsAbs in MM, with a special focus on their optimal dosing schedule, resistance mechanisms and future strategies to enhance efficacy, reduce toxicity, and maximize duration of response.

EXPERT OPINION

To further improve the efficacy of BsAbs, ongoing studies are investigating whether combination therapy can enhance depth and duration of response. An important open question is also to what extent response to BsAbs can be improved when these agents are used in earlier lines of therapy. In addition, more evidence is needed on rational de-intensification strategies of BsAb dosing upon achieving a sufficient response, and if (temporary) treatment cessation is possible in patients who have achieved a deep remission (e.g. complete response or minimal residual disease-negative status).

Correlation of immune fitness with response to teclistamab in relapsed/refractory multiple myeloma in the MajesTEC-1 study

ABSTRACT

Teclistamab, an off-the-shelf B-cell maturation antigen (BCMA) × CD3 bispecific antibody that mediates T-cell activation and subsequent lysis of BCMA-expressing myeloma cells, is approved for the treatment of patients with relapsed/refractory multiple myeloma (R/RMM). As a T-cell redirection therapy, clinical outcomes with teclistamab may be influenced by patient immune fitness and tumor antigen expression. We correlated tumor characteristics and baseline immune profiles with clinical response and disease burden in patients with R/RMM from the pivotal phase 1/2 MajesTEC-1 study, focusing on patients treated with 1.5 mg/kg of teclistamab (N = 165). Peripheral blood samples were collected at screening, and bone marrow samples were collected at screening and cycle 3. Better clinical outcomes to teclistamab correlated with higher baseline total T-cell counts in the periphery. In addition, responders (partial response or better) had a lower proportion of immunosuppressive regulatory T cells (Tregs), T cells expressing coinhibitory receptors (CD38, PD-1, and PD-1/TIM-3), and soluble BCMA and a T-cell profile suggestive of a more cytolytic potential, compared with nonresponders. Neither frequency of baseline bone marrow BCMA expression nor BCMA-receptor density was associated with clinical response to teclistamab. Improved progression-free survival was observed in patients with a lower frequency of T cells expressing exhaustion markers and immunosuppressive Tregs. Overall, response to teclistamab was associated with baseline immune fitness; nonresponders had immune profiles suggestive of immune suppression and T-cell dysfunction. These findings illustrate the importance of the contribution of the immune landscape to T-cell redirection therapy response. This trial was registered at www.ClinicalTrials.gov as #NCT03145181/NCT04557098.

Deciphering the genetics and mechanisms of predisposition to multiple myeloma

Multiple myeloma (MM) is an incurable malignancy of plasma cells. Epidemiological studies indicate a substantial heritable component, but the underlying mechanisms remain unclear. Here, in a genome-wide association study totaling 10,906 cases and 366,221 controls, we identify 35 MM risk loci, 12 of which are novel. Through functional fine-mapping and Mendelian randomization, we uncover two causal mechanisms for inherited MM risk: longer telomeres; and elevated levels of B-cell maturation antigen (BCMA) and interleukin-5 receptor alpha (IL5RA) in plasma. The largest increase in BCMA and IL5RA levels is mediated by the risk variant rs34562254-A at TNFRSF13B. While individuals with loss-of-function variants in TNFRSF13B develop B-cell immunodeficiency, rs34562254-A exerts a gain-of-function effect, increasing MM risk through amplified B-cell responses. Our results represent an analysis of genetic MM predisposition, highlighting causal mechanisms contributing to MM development.

Just scratching the surface: novel treatment approaches for multiple myeloma targeting cell membrane proteins

A better understanding of the roles of the adaptive and innate immune systems in the oncogenesis of cancers including multiple myeloma (MM) has led to the development of novel immune-based therapies. B cell maturation antigen (BCMA), G protein-coupled receptor family C group 5 member D (GPRC5D) and Fc receptor-like protein 5 (FcRL5, also known as FcRH5) are cell-surface transmembrane proteins expressed by plasma cells, and have been identified as prominent immunotherapeutic targets in MM, with promising activity demonstrated in patients with heavily pretreated relapsed and/or refractory disease. Indeed, since 2020, antibody-drug conjugates, bispecific T cell engagers and autologous chimeric antigen receptor T cells targeting BCMA or GPRC5D have been approved for the treatment of relapsed and/or refractory MM. However, responses to these therapies are not universal, and acquired resistance invariably occurs. In this Review, we discuss the various immunotherapeutic approaches targeting BCMA, GPRC5D and FcRL5 that are currently either available or in clinical development for patients with MM. We also review the mechanisms underlying resistance to such therapies, and discuss potential strategies to overcome these mechanisms and improve patient outcomes.

Next-Generation Therapies for Multiple Myeloma

Recent therapeutic advances have significantly improved the outcome for patients with multiple myeloma (MM). The backbone of successful standard therapy is the combination of Ikaros degraders, glucocorticoids, and proteasome inhibitors that interfere with the integrity of myeloma-specific superenhancers by directly or indirectly targeting enhancer-bound transcription factors and coactivators that control expression of MM dependency genes. T cell engagers and chimeric antigen receptor T cells redirect patients' own T cells onto defined tumor antigens to kill MM cells. They have induced complete remissions even in end-stage patients. Unfortunately, responses to both conventional therapy and immunotherapy are not durable, and tumor heterogeneity, antigen loss, and lack of T cell fitness lead to therapy resistance and relapse. Novel approaches are under development to target myeloma-specific vulnerabilities, as is the design of multimodality immunological approaches, including and beyond T cells, that simultaneously recognize multiple epitopes to prevent antigen escape and tumor relapse.

Therapeutic progress in relapsed/refractory multiple myeloma

Improvement in the therapeutics for multiple myeloma (MM) has been continuously developed owing to the application of novel drugs and technologies in the last 20 years. The standard first-line therapy for MM consists of a three-drug induction regimen based on immunomodulatory drugs and proteasome inhibitors combined with autologous stem cell transplantation. However, MM remains incurable; therefore, therapies for relapsed/refractory MM (RRMM) are emerging and evolving rapidly. This study aimed to summarize and review the results of RRMM trials over the past 5 years to provide a holistic overview and insights for practitioners in related fields and to provide additional ideas for clinical trialists. This study shows that daratumumab and isatuximab continue to significantly advance as treatment options. Additionally, novel antibody drugs, such as elotuzumab and selinexor, as well as bispecific antibodies, teclistamab and talquetamab, are currently undergoing clinical research with promising outcomes. However, chimeric antigen receptor-T cell therapy targeting B-cell maturation antigen remains the optimal approach for MM treatment.

Biomarkers of Efficacy and Safety of the Academic BCMA-CART ARI0002h for the Treatment of Refractory Multiple Myeloma

PURPOSE

B-cell maturation antigen (BCMA)-chimeric antigen receptor T-cells (CART) improve results obtained with conventional therapy in the treatment of relapsed/refractory multiple myeloma. However, the high demand and expensive costs associated with CART therapy might prove unsustainable for health systems. Academic CARTs could potentially overcome these issues. Moreover, response biomarkers and resistance mechanisms need to be identified and addressed to improve efficacy and patient selection. Here, we present clinical and ancillary results of the 60 patients treated with the academic BCMA-CART, ARI0002h, in the CARTBCMA-HCB-01 trial.

PATIENTS AND METHODS

We collected apheresis, final product, peripheral blood and bone marrow samples before and after infusion. We assessed BCMA, T-cell subsets, CART kinetics and antibodies, B-cell aplasia, cytokines, and measurable residual disease by next-generation flow cytometry, and correlated these to clinical outcomes.

RESULTS

At cut-off date March 17, 2023, with a median follow-up of 23.1 months (95% CI, 9.2-37.1), overall response rate in the first 3 months was 95% [95% confidence interval (CI), 89.5-100]; cytokine release syndrome (CRS) was observed in 90% of patients (5% grades ≥3) and grade 1 immune effector cell-associated neurotoxicity syndrome was reported in 2 patients (3%). Median progression-free survival was 15.8 months (95% CI, 11.5-22.4). Surface BCMA was not predictive of response or survival, but soluble BCMA correlated with worse clinical outcomes and CRS severity. Activation marker HLA-DR in the apheresis was associated with longer progression-free survival and increased exhaustion markers correlated with poorer outcomes. ARI0002h kinetics and loss of B-cell aplasia were not predictive of relapse.

CONCLUSIONS

Despite deep and sustained responses achieved with ARI0002h, we identified several biomarkers that correlate with poor outcomes.

Bispecific antibodies for the treatment of relapsed/refractory multiple myeloma: updates and future perspectives

Patients with relapsed/refractory multiple myeloma (RRMM) that are refractory to the five most active anti-MM drugs, so-called penta-refractory MM, have historically had dismal outcomes with subsequent therapies. Progressive immune dysfunction, particularly of the T-cell repertoire, is implicated in the development of disease progression and refractory disease. However, the advent of novel immunotherapies such as bispecific antibodies are rapidly changing the treatment landscape and improving the survival outcomes of patients with RRMM. Bispecific antibodies are antibodies that are engineered to simultaneously engage cytotoxic immune effector cells (T cells or NK cells) and malignant plasma cells via binding to immune effector cell antigens and extracellular plasma cell antigens leading to immune effector cell activation and malignant plasma cell destruction. Currently, bispecific antibodies that bind CD3 on T cells and plasma cell epitopes such as B-cell maturation antigen (BCMA), G-protein coupled receptor family C group 5 member D (GPRC5d), and Fc receptor homologue 5 (FcRH5) are the most advanced in clinical development and are showing unprecedented response rates in patients with RRMM, including patients with penta-refractory disease. In this review article, we explore the available clinical data of bispecific antibodies in RRMM and summarize the efficacy, safety, toxicity, clinical outcomes, mechanisms of resistance, and future directions of these therapies in patients with RRMM.

CD8 effector T cells enhance teclistamab response in BCMA-exposed and -naïve multiple myeloma

ABSTRACT

Teclistamab, a B-cell maturation antigen (BCMA)- and CD3-targeting bispecific antibody, is an effective novel treatment for relapsed/refractory multiple myeloma (R/RMM), but efficacy in patients exposed to BCMA-directed therapies and mechanisms of resistance have yet to be fully delineated. We conducted a real-world retrospective study of commercial teclistamab, capturing both clinical outcomes and immune correlates of treatment response in a cohort of patients (n = 52) with advanced R/RMM. Teclistamab was highly effective with an overall response rate (ORR) of 64%, including an ORR of 50% for patients with prior anti-BCMA therapy. Pretreatment plasma cell BCMA expression levels had no bearing on response. However, comprehensive pretreatment immune profiling identified that effector CD8+ T-cell populations were associated with response to therapy and a regulatory T-cell population associated with nonresponse, indicating a contribution of immune status in outcomes with potential utility as a biomarker signature to guide patient management.

Soluble B-cell maturation antigen in multiple myeloma

B-cell maturation antigen (BCMA) has emerged as a promising immunotherapeutic target in multiple myeloma (MM) management, with the successive approval of antibody-drug conjugates, bispecific antibodies, and chimeric antigen receptor T-cell therapies directed to this membrane receptor. Soluble BCMA (sBCMA), a truncated version produced through gamma-secretase cleavage, can be quantified in serum/plasma samples from patients with MM via electrochemiluminescence, fluorescence, or enzyme-linked immunosorbent assays, as well as through mass spectrometry-based proteomics. Besides its short serum half-life and independence from kidney function, sBCMA represents a reliable and convenient tool for MM monitoring in patients with nonsecretory or oligosecretory disease. Numerous studies have suggested a potential utility of this bioanalyte in the risk stratification of premalignant plasma cell disorders, diagnosis and prognostication of MM, and response evaluation following anti-myeloma therapies. In short, sBCMA might be the "Swiss army knife" of MM laboratory testing, but is it ready for prime time?

BCMA- or GPRC5D-targeting bispecific antibodies in multiple myeloma: efficacy, safety, and resistance mechanisms

ABSTRACT

Bispecific antibodies that engage T cells to target B-cell maturation antigen or G-protein-coupled receptor class C group 5 member D have demonstrated remarkable efficacy in heavily pretreated relapsed or refractory multiple myeloma (MM), leading to the recent accelerated approval of teclistamab, elranatamab, and talquetamab by health agencies. Future challenges, however, remain to define their optimal dosing schedule and duration, sequencing, and integration with established anti-MM therapeutics as well as delineating the biological and clinical mediators of immune escape.

Teclistamab: Mechanism of action, clinical, and translational science

Multiple myeloma (MM) remains incurable despite improvements in treatment options. B-cell maturation antigen (BCMA) is predominantly expressed in B-lineage cells and represents a promising new target for MM. Teclistamab (TECVAYLITM ) is the first T-cell redirecting bispecific antibody approved for patients with MM. Targeting both CD3 receptor complex on T cells and BCMA on myeloma cells, teclistamab leads to T-cell activation and subsequent lysis of BCMA+ cells. The recommended dose of teclistamab is 1.5 mg/kg subcutaneous weekly after two step-up doses of 0.06 and 0.3 mg/kg, which was selected after review of safety, efficacy, pharmacokinetic, and pharmacodynamic data. Exposure-response analyses of efficacy and safety data were also used to confirm the teclistamab dose. Teclistamab resulted in a high rate of deep and durable responses (63% overall response, 45.5% complete response or better, with 22 months median duration of response) in patients with triple-exposed relapsed/refractory MM. Common adverse reactions included cytokine release syndrome, hematologic abnormalities, and infections. Teclistamab is currently being investigated as monotherapy as well as combination therapy across different MM indications.

Rare oncology therapeutics: review of clinical pharmacology package of drug approvals (2019-2023) by US FDA, best practices and recommendations

There are many challenges with rare diseases drug development and rare oncology indications are not different. To understand the regulatory landscape as it relates to application of clinical pharmacology principles in rare oncology product development, we reviewed publicly available information of 39 approvals by US FDA between January 2019 and March 2023. The objective was to understand the expected clinical pharmacology studies and knowledge base in such approvals. Model informed drug development (MIDD) applications were also reviewed, as such approaches are expected to play a critical role in filling clinical pharmacology gaps in rare oncology, where number of clinical trials and size of these trials will perhaps continue to be small. The findings highlighted how clinical pharmacology contributed to the evidence of effectiveness, dose optimization and elucidation of intrinsic and extrinsic factors affecting drug's behavior. Clinical pharmacology studies were often integrated with modeling in many of the NDAs/BLAs. Of the post marketing requirements (PMR) received, 18% were for dose optimization, 49% for DDI, 8% for QTc, 49% for specific population, and 5% for food effect. Two post marketing commitments (PMC) were issued for immunogenicity of the 11 biologics submissions. 15% (6 of 39) of the submissions used maximum tolerated dose (MTD) to advance their molecule into Phase 2 studies. Of them 3 approvals received PMR for dose optimization. 3 + 3 was the most prevalent Phase 1 design with use in 74% of the New Drug Applications (NDA)/Biologic License Applications (BLA) reviewed. Rest used innovative approaches such as BLRM, BOIN or mTPi, with BLRM being the most common. Seamless clinical pharmacology and MIDD approaches are paramount for rare oncology drug development.

Population Pharmacokinetics and Exposure-Response with Teclistamab in Patients With Relapsed/Refractory Multiple Myeloma: Results From MajesTEC-1

BACKGROUND

Teclistamab, a B-cell maturation antigen × CD3 bispecific antibody, is approved in patients with relapsed/refractory multiple myeloma (RRMM) who have previously received an immunomodulatory agent, a proteasome inhibitor, and an anti-CD38 antibody.

OBJECTIVE

We report the population pharmacokinetics of teclistamab administered intravenously and subcutaneously (SC) and exposure-response relationships from the phase I/II, first-in-human, open-label, multicenter MajesTEC-1 study.

METHODS

Phase I of MajesTEC-1 consisted of dose escalation and expansion at the recommended phase II dose (RP2D; 1.5 mg/kg SC weekly, preceded by step-up doses of 0.06 and 0.3 mg/kg); phase II investigated the efficacy of teclistamab RP2D in patients with RRMM. Population pharmacokinetics and the impact of covariates on teclistamab systemic exposure were assessed using a 2-compartment model with first-order absorption for SC and parallel time-independent and time-dependent elimination pathways. Exposure-response analyses were conducted, including overall response rate (ORR), duration of response (DoR), progression-free survival (PFS), overall survival (OS), and the incidence of grade ≥ 3 anemia, neutropenia, lymphopenia, leukopenia, thrombocytopenia, and infection.

RESULTS

In total, 4840 measurable serum concentration samples from 338 pharmacokinetics-evaluable patients who received teclistamab were analyzed. The typical population value of time-independent and time-dependent clearance were 0.449 L/day and 0.547 L/day, respectively. The time-dependent clearance decreased rapidly to < 10% after 8 weeks of teclistamab treatment. Patients who discontinue teclistamab after the 13th dose are expected to have a 50% reduction from Cmax in teclistamab concentration at a median (5th to 95th percentile) time of 15 days (7-33 days) after Tmax and a 97% reduction from Cmax in teclistamab concentration at a median time of 69 days (32-163 days) after Tmax. Body weight, multiple myeloma type (immunoglobulin G vs non-immunoglobulin G), and International Staging System (ISS) stage (II vs I and III vs I) were statistically significant covariates on teclistamab pharmacokinetics; however, these covariates had no clinically relevant effect on the efficacy of teclistamab at the RP2D. Across all doses, ORR approached a plateau at the concentration range associated with RP2D, and in patients who received the RP2D, a flat exposure-response curve was observed. No apparent relationship was observed between DoR, PFS, OS, and the incidence of grade ≥3 adverse events across the predicted exposure quartiles.

CONCLUSION

Body weight, myeloma type, and ISS stage impacted systemic teclistamab exposure without any clinically relevant effect on efficacy. The exposure-response analyses for ORR showed a positive trend with increasing teclistamab systemic exposure, with a plateau at the RP2D, and there was no apparent exposure-response trend for safety or other efficacy endpoints. These analyses support the RP2D of teclistamab in patients with RRMM.

CLINICAL TRIAL REGISTRATION

NCT03145181 (phase I, 09 May 2017); NCT04557098 (phase II, 21 September 2020).

T-cell redirecting bispecific antibodies in multiple myeloma: Current landscape and future directions

T-cell engaging bispecific antibodies (BsAbs) have substantial activity in heavily pretreated patients with multiple myeloma (MM). The overall response rate obtained with B-cell maturation antigen (BCMA)-targeting BsAbs is approximately 60%-70%, including a high proportion of patients achieving very good partial response or complete response. Comparable efficacy is seen with BsAbs targeting GPRC5D or FcRH5. Cytokine release syndrome is frequently observed with BsAb treatment, but mostly during the step-up doses and the first full dose. Early intervention with IL-6 receptor blocking antibodies (e.g., tocilizumab) prevents escalation to severe manifestations. Infections are also common during treatment and related to the extent of exposure to immune suppressive anti-MM agents, as well as development of hypogammaglobulinemia due to elimination of normal plasma cells, and probably because of T-cell exhaustion resulting from continuous BsAb-mediated T-cell activation. Adequate monitoring for infections and institution of infectious prophylaxis are essential. Patients treated with GPRC5D-targteing BsAbs often develop skin and nail disorders and loss of taste, which is likely related to GPRC5D expression in cells that produce hard keratin. Currently ongoing studies are aiming at further improving these results by evaluating BsAbs in combination with other drugs, such as immunomodulatory agents and anti-CD38 antibodies, as well as the application of BsAbs in earlier lines of therapy, including patients with newly diagnosed disease. We expect that the outcomes of patients with MM will further improve by the introduction of this novel type of T-cell immunotherapy.

Prospective Assessment of Tumour Burden and Bone Disease in Plasma Cell Dyscrasias Using DW-MRI and Exploratory Bone Biomarkers

Novel biomarkers for tumour burden and bone disease are required to guide clinical management of plasma cell dyscrasias. Recently, bone turnover markers (BTMs) and Diffusion-Weighted Magnetic Resonance Imaging (DW-MRI) have been explored, although their role in the prospective assessment of multiple myeloma (MM) and monoclonal gammopathy of undetermined significance (MGUS) is unclear. Here, we conducted a pilot observational cohort feasibility study combining serum BTMs and DW-MRI in addition to standard clinical assessment. Fifty-five patients were recruited (14 MGUS, 15 smouldering MM, 14 new MM and 12 relapsed MM) and had DW-MRI and serum biomarkers (P1NP, CTX-1, ALP, DKK1, sclerostin, RANKL:OPG and BCMA) measured at baseline and 6-month follow-up. Serum sclerostin positively correlated with bone mineral density (r = 0.40-0.54). At baseline, serum BCMA correlated with serum paraprotein (r = 0.42) and serum DKK1 correlated with serum free light chains (r = 0.67); the longitudinal change in both biomarkers differed between International Myeloma Working Group (IMWG)-defined responders and non-responders. Myeloma Response Assessment and Diagnosis System (MY-RADS) scoring of serial DW-MRI correlated with conventional IMWG response criteria for measuring longitudinal changes in tumour burden. Overall, our pilot study suggests candidate radiological and serum biomarkers of tumour burden and bone loss in MM/MGUS, which warrant further exploration in larger cohorts to validate the findings and to better understand their clinical utility.

Teclistamab: First Approval

Teclistamab (TECVAYLI®), a bispecific antibody that targets CD3 and B cell maturation antigen (BCMA), is being developed by Janssen Research and Development for the treatment of relapsed or refractory multiple myeloma. Teclistamab was recently granted conditional approval in the EU for the treatment of adult patients with relapsed and refractory multiple myeloma who have received three or more prior therapies (including an immunomodulatory agent, a proteasome inhibitor and an anti-CD38 antibody) and have demonstrated disease progression on the last therapy. Teclistamab was subsequently approved in the US for the treatment of adult patients with relapsed or refractory multiple myeloma who have received at least four prior lines of therapy (including an immunomodulatory agent, a proteasome inhibitor and an anti-CD38 antibody). This article summarizes the milestones in the development of teclistamab leading to this first approval for relapsed or refractory multiple myeloma.